1. Field of the Invention
The invention relates generally to motor-driven food preparation devices, and more specifically to a coupling connecting a blender motor to a blender blade assembly which can accommodate misalignment of a blender jar with a blender base.
2. Description of the Related Art
Blenders are a common motor-driven appliance in home, commercial, and institutional kitchens. FIG. 1A illustrates in a sectional view a conventional prior art blender assembly 10 comprising a jar 12 and a motorized base 14. The jar 12 comprises a perimeter wall 20 and a bottom wall 44 which together define a chamber 22 adapted to hold a food item (not shown). The perimeter wall 20 transitions to a downwardly-extending skirt 24 which defines with the bottom wall 44 a skirt recess 40.
A rotating blade assembly 26 for processing food items in the chamber 22 is mounted to the jar 12. The blade assembly 26 comprises a bushing assembly 30 mounted within an opening in the bottom wall 44 of the jar 12 and a drive shaft 34 rotatably mounted to the bushing assembly 30 and defines an axis of rotation 42. A blade 28 is mounted to one end of the drive shaft 34 and a male coupler 32 is mounted to the other end of the drive shaft 34.
The motorized base 14 comprises a base housing 50 enclosing a drive motor 52. The armature of the drive motor 52 terminates in an output shaft 54 which mounts a female coupler 56. The output shaft 54 defines a second axis of rotation 64. The base housing 50 transitions upwardly to a jar pedestal 62 adapted for cooperative registry with the skirt recess 40 when the jar 12 is seated on the base 14.
Referring to FIG. 1B, the male coupler 32 is a disk-shaped, gear-like body having a circumscribing perimeter surface 36 that ends in opposing upper and lower edges 46, 48, respectively, having a plurality of regularly-spaced longitudinal splines 38 having tips that form the perimeter surface.
The female coupler 56 is a somewhat cup-shaped body having a circumferential inner surface 58 from which project a plurality of regularly-spaced longitudinal splines 60, which are complementary to the splines 38 on the male coupler for cooperative registry with the male coupler 32 to effect rotation of the mixing blades 28 by rotation of the drive motor 52.
When the jar 12 is properly seated on the motorized base 14, the jar pedestal 62 will be received in the skirt recess 40 so that the drive shaft rotational axis 42 and the output shaft rotational axis 64 are coaxial. However, in some instances, the jar 12 may be unintentionally seated on the motorized base 14 so that the blade assembly rotational axis 42 is misaligned relative to the drive motor rotational axis 64 as seen in FIGS. 1A and 1B. This misalignment will cause the male coupler 32 to improperly seat in the female coupler 56, resulting in the upper and lower edges 46, 48 of the male coupler 32 contacting the inner surface of the female coupler 56 as the tip of each male coupler spline 38 is received between adjacent female splines 60. The misalignment results in asymmetric rotation of the male coupler 32 relative to the female coupler 56 and the contacting of the edges 46, 48 with the inner surface 58 causes excessive vibration and noise, as well as accelerated wear of the couplers 32, 56.